1. Field of Invention
Exemplary aspects of the present invention relate to a light source unit including: an arc tube having a light emitting section in which discharging emission between electrodes is performed and sealed sections provided at both ends of the light emitting section; an elliptic reflector to emit a luminous flux radiated from the arc tube in a certain uniform direction; and a secondary reflecting mirror having a reflecting surface opposed to a reflecting surface of the elliptic reflector, covering the front side of the arc tube in the direction of emission of the luminous flux and reflecting the luminous flux radiated from the arc tube toward the elliptic reflector, and a projector having the light source unit, and a method of manufacturing the light source unit.
2. Description of Related Art
In the related art, a projector to enlarge and project an optical image by modulating a luminous flux emitted from a light source according to image information is used. Such a projector is used for presentations in conferences or the like with a personal computer. Also, in response to a desire to view movies or the like, on a large screen at home, this kind of projector is used for a home theater.
As a light source for this type of projector, an electric discharging arc tube, such as a metal halide lamp, or a high-pressure mercury lamp is used. The electric discharging arc tube includes a spherical light emitting section in which discharging emission is carried out between a pair of electrodes disposed at a distance from each other, and sealed sections provided at both ends of the light emitting section and containing metal foil to apply voltage to the electrodes therein.
As regards the electric discharging arc tube, as described in JP-A-8-69775 (See [0020] and FIG. 2), for example, an electric discharging arc tube formed with a reflecting and thermal insulating film containing silica/alumina deposited thereon on the front portion of the light-emitting section on the luminous flux outgoing side is proposed.
According to this type of electric discharging arc tube, since the luminous flux radiated from the light-emitting section is converted into heat at the reflecting and thermal insulating film, which contributes to an increase in temperature in the light-emitting section, a vapor pressure of an additive in the arc tube, such as halogen, can be stabilized, whereby unevenness of color or unevenness of illumination intensity of the projected image of the projector caused by the electric discharging arc tube can be reduced or prevented.